Corrosion inhibitory studies of an eco-friendly thiourea derivative of amino acid on aluminium using 0.1M HCl solution

Abstract

The inhibition efficiency and corrosion rate of aluminium were investigated at varying temperatures and immersion time using thiourea complex with an organic ligand at concentrations of 0.20, 0.40, 0.60, 0.80 and 1.00 M. The results showed that an increase in the concentration of the complex thiourea led to an increase in the inhibition efficiency, which was attributed to the availability of the proton moiety of the thiourea lost as electron in acidic media. The inhibition efficiency decreased as the immersion time increased with temperature and the largest decrease observed at 333 K due to the distortion of molecular structure of the complex thiourea at high temperatures. The corrosion rate decreased with an increase in immersion time but increased with temperature, possibly due to inhibitor molecular rearrangement. The activation energy of the suppression process of high-concentration thiourea was found to be higher than that of low-concentration, indicating that the adsorption process was triggered by physical adsorption. The formation of a thin film on the metal surface was due to the presence of complex thiourea acted as a barrier to both energy and mass transport, leading to an increase in the activation energy. The adsorption of the thiourea derivatives complex on aluminum was primarily physisorption. The Langmuir, Flory-Huggins, Tempkin, and Dubinin-Radushkevich adsorption isotherm models were investigated with Langmuir found to be the most fitted model based on high R2 values of the model.